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The Ultimate List of Deductible Business Expenses (2026 Guide for San Diego Small Businesses)

If you’re a small business owner in Carlsbad, Oceanside, Vista, or anywhere in San Diego County, you’ve probably asked:

“What can I actually deduct as a business expense?”

Whether you run a construction company, plumbing business, HVAC service, marketing agency, coffee shop, or design firm, understanding deductible expenses can significantly reduce your taxable income — and keep more cash in your business.

At Accounting Fresh CPA Inc., we help local business owners maximize deductions while staying compliant. Here’s your ultimate guide.


What Is a Deductible Business Expense?

The Internal Revenue Service (IRS) defines a deductible expense as one that is:

  • Ordinary (common in your industry)
  • Necessary (helpful and appropriate for your business)

If it meets those two criteria, there’s a good chance it’s deductible.


The Ultimate List of Deductible Business Expenses

1. Advertising & Marketing

Marketing is fully deductible.

Examples:

  • Google Ads & Facebook Ads
  • Website hosting & design
  • SEO services
  • Business cards & flyers
  • Sponsorships (local sports teams, events)
  • Branded apparel with logo

👉 For local San Diego contractors, this includes HomeAdvisor, Yelp Ads, and local chamber memberships.


2. Vehicle & Mileage

If you use your vehicle for business:

  • Standard mileage rate (per IRS rate)
  • Gas
  • Repairs & maintenance
  • Insurance
  • Registration
  • Lease payments
  • Depreciation (if owned)

Construction & trades businesses often save thousands here.

Pro Tip: You must track business vs personal use.


3. Equipment & Tools

Especially important for contractors and trades:

  • Power tools
  • Ladders
  • Heavy equipment
  • Computers
  • Monitors
  • iPads for field estimates

Large purchases may qualify for:

  • Section 179 deduction
  • Bonus depreciation

4. Office Expenses

  • Office supplies
  • Printer & ink
  • Postage
  • Furniture
  • Internet
  • Phone bills
  • Software subscriptions

If you use QuickBooks Online, Buildertrend, ServiceTitan, Monday.com — those are deductible.


5. Home Office Deduction

If you work from home in a dedicated space:

  • Portion of rent or mortgage
  • Utilities
  • Internet
  • Property taxes
  • Home insurance

Must be used regularly and exclusively for business.


6. Rent (Office, Warehouse, Shop)

If you lease:

  • Office space
  • Retail storefront
  • Storage unit
  • Equipment yard

Rent is fully deductible.


7. Wages & Payroll

  • Employee wages
  • Payroll taxes
  • Health insurance
  • Workers comp
  • Employer retirement contributions
  • Bonuses

If you’re an S-Corp owner, your W-2 wages are deductible to the business.


8. Contract Labor

1099 subcontractors:

  • Electricians
  • Framers
  • Designers
  • Freelancers
  • Bookkeepers

Make sure you file 1099-NEC forms properly.


9. Insurance

Business-related insurance is deductible:

  • General liability
  • Professional liability
  • Commercial auto
  • Workers compensation
  • Cyber liability
  • Umbrella policies

10. Professional Fees

  • CPA fees
  • Bookkeeping
  • Tax preparation
  • Legal fees
  • Business consulting

Yes — hiring a CPA is deductible.


11. Business Meals

Typically 50% deductible (current IRS rules).

Examples:

  • Client lunches
  • Vendor meetings
  • Business travel meals

Must be business-related and documented.


12. Travel

  • Flights
  • Hotels
  • Rental cars
  • Uber/Lyft
  • Parking
  • Tolls

Must be primarily for business purposes.


13. Education & Training

  • Continuing education
  • Certifications
  • Industry conferences
  • Trade association dues
  • Online courses

Great for contractors upgrading licenses or certifications.


14. Interest & Bank Fees

  • Business loan interest
  • Line of credit interest
  • Equipment financing
  • Bank service charges
  • Merchant processing fees (Stripe, Square)

15. Depreciation

Large purchases can often be deducted over time:

  • Vehicles
  • Machinery
  • Furniture
  • Computers
  • Office build-outs

Strategic depreciation planning can significantly reduce taxable income.


Common Expenses That Are NOT Deductible

  • Personal groceries
  • Personal clothing (unless branded uniforms)
  • Commuting miles (home to office)
  • Personal gym memberships
  • Fines & penalties

Special Considerations for San Diego Contractors & Trades

Construction and service businesses in Carlsbad and North County often miss:

  • Job costing software subscriptions
  • Fuel allocation between vehicles
  • Equipment repairs vs capitalization
  • Inventory tracking
  • Sales tax handling
  • Owner health insurance deduction

If you’re a plumber, electrician, HVAC contractor, remodeler, landscaper, or concrete contractor — your deductions can be complex.


Don’t Forget: Structure Matters

Your deductions may vary depending on whether you’re:

  • Sole proprietor
  • LLC
  • S-Corporation
  • Partnership

For example:

  • S-Corp owners must pay reasonable wages
  • QBI deduction rules may apply
  • Payroll strategy impacts tax savings

Proper structure can save tens of thousands annually.


Final Thoughts: Keep More of What You Earn

The difference between average bookkeeping and strategic accounting is often thousands of dollars in missed deductions.

If you’re a small business owner in:

  • Carlsbad
  • Oceanside
  • Vista
  • Encinitas
  • San Marcos
  • Anywhere in San Diego County

We can help you:

  • Track expenses properly
  • Maximize deductions
  • Reduce audit risk
  • Plan proactively for taxes

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